A wireless personal area network (WPAN) realizes a personal area network (PAN) in a wireless way. As a representative WPAN, there is known a wireless sensor network (WSN). WSN is a core technology as a basis of a ubiquitous network and has wide applications in various fields such as environment monitoring, medical systems, telematics, home networks, and logistics systems. Zigbee, which defines standards of upper layers including network layers based on the IEEE 802 15.4 MAC/PHY standard which is a standard technology applied to WSN, is designed to maintain low power consumption and low speed characteristics of IEEE 802.15.4.
Zigbee has a network layer based on non-IP, which does not directly interwork with an IP network. A Zigbee protocol method is inefficient because in order to communicate with an IP network, packets should be collected through certain collecting equipment and reprocessed in an application layer. If a sensor node in a terminal has an IP address, the sensor node can be individually accessed and naturally integrated with the most broadly constructed IP network. That is, without a collecting device or a relay device at an intermediate point, direct one-to-one communication becomes possible. As a technology for allowing interworking the WPAN and an external network to interact with each other by utilizing IPv6, there is known an IPv6 over low power wireless personal area network (6LoWPAN) of which standardization has been studied by the 6LoWPAN Working Group.
FIG. 1 illustrates a conceptual diagram of a network in which 6LoWPAN is implemented in accordance with a conventional technology.
With reference to FIG. 1, WPAN 10 is connected to an external IP network 20 via a gateway 30. In addition, IP communication is accomplished between a host existing on the IP network 20 and a device existing on the WPAN 10 based on Internet protocol. That is, on the network in which the 6LowPAN is implemented, if an IPv6 address is informed, a packet can be directly transmitted and received between an external host and an internal WPAN 10 node without needing to perform a conversion process of a communication protocol such as Zigbee.
In order to implement such a network, a node of the WPAN 10 has an IPv6 address. In order to generate an IPv6 address of a node, there is employed a method using an extended unique identifier (EUI)-64. An IPv6 address generated by EUI-64 is globally unique and can provide a mobile support between the WPAN 10 and the IP network 20.
However, the WPAN 10, in which PHY/MAC layers are defined by IEEE 802.15.4, uses small-sized packets. In consideration of the maximum size of information unit used by PHY/MAC in the WPAN 10, an IPv6/TCP or IPv6/UDP header and application data should be expressed within 80 bytes. As a result, in order to store as much data as possible in a single packet, the IPv6 packet header needs to be compressed.